\begin{frame}
  \frametitle{Group Example}

  Group example:
  \smallskip
  
  \begin{block}{}
  \begin{center}
  $\begin{array}{lcl}
  e\cdot x&=&x\\
  I(x)\cdot x&=&e\\
  (x\cdot y)\cdot z &=& x\cdot (y\cdot z)
  \end{array}$
  \end{center}
  \end{block}
  
  \bigskip\bigskip\pause
  First we give these equations a `sensible' orientation:
  \smallskip
  
  \begin{block}{}
  \begin{center}
  $\begin{array}{llcl}
  (1)&e\cdot x&\to&x\\
  (2)&I(x)\cdot x&\to&e\\
  (3)&(x\cdot y)\cdot z &\to& x\cdot (y\cdot z)
  \end{array}$
  \end{center}
  \end{block}
\end{frame}